The vitamin D receptor (VDR) is a nuclear hormone receptor that regulates cell proliferation, cell differentiation, and calcium homeostasis. The receptor contains several functional domains, including a DNA binding domain (VDR-DBD) and a ligand-binding domain (VDR-LBD), which mediates ligand-dependent gene regulation. VDR binds DNA as a heterodimer with the retinoid X receptor (RXR). The receptor is activated by vitamin D analogs that induce the disruption of VDR-corepressor binding and promote VDR-coactivator interactions. The interactions between VDR and coregulators are essential for VDR-mediated transcription.
The gene product of TRPV6 (ECaC2 or CaT1) is a membrane Ca2+ ion channel, which is highly expressed in advanced prostate cancer and may be directly regulated by VDR in the presence of 1,25-(OH)2D3.